This invention relates to a flexible pipe inserter and more particularly to apparatus for inserting a flexible pipe into an old, larger size pipeline system, such as systems employed to distribute natural gas and the like.
As is well known in the art to which my invention relates, many natural gas distribution companies are experiencing corrosion and leakage problems in their old cast iron pipeline systems. This is especially true due to the fact that most of such cast iron pipe is in the central business districts of towns and cities or areas of high population density. Since such gas mains are buried in streets with wide pavement and sidewalks and such mains are also in close contact with other underground untilities, it is very difficult and expensive to replace old cast iron mains with new mains.
It has become increasingly popular to replace old cast iron mains by inserting long sections of plastic pipe into the old pipe with such sections usually being block-long sections. This method of replacing old mains eliminates most of the ditch excavation normally required for new pipe burial. Also, the old cast iron serves as a casing to provide some protection for the plastic pipe from external hazards. Accordingly, the insertion of plastic pipe into old cast iron mains is considerably cheaper in high density areas than direct burial replacement. At the present time, most of the plastic pipe is inserted into smaller diameter cast iron pipelines ranging from approximately 2 inches to 6 inches in size. Since such small size plastic pipe is usually of the polyethylene type, it is relatively easy to handle due to the flexibility of such pipe. Also, since this type pipe is usually manufactured and sold in 500 foot coils, it is particularly adapted for insertion in an old cast iron pipeline.
Heretofore, it has been the normal procedure to use manual labor in the insertion of the plastic pipe into the old cast iron pipeline. This is not only a laborious and tiring method but it requires three men to accomplish a block-long insertion. In actual practice, I have found that the maximum length of 11/4 inch plastic pipe that can be inserted manually ranges from approximately 400 to 450 feet and also requires approximately 20 to 30 minutes.